The invention relates to the field of cosmetic product dispensers known as sticks, the cosmetic products so dispensed being typically paste-like, and most often deodorants.
Known stick type dispensers most often include:
a body forming a skirt or a tubular lateral wall containing a cosmetic product propellant device as a solid or semi-solid stick, and open at its two ends, the cosmetic product having to show on the surface at the upper end in order to be applied, said tubular wall, open at its two ends, possibly including a bottom,
a cap or top closing the upper end, typically in a leakproof way,
a propellant device typically including two parts mobile one relative to the other, one being constituted by a piston in the form of a nut adjusted to the shape of the body, the piston, which supports the cosmetic product, being typically movable ax-ally but not in rotation, either because of the non-cylindrical shape of the body, or, if the body is cylindrical, by the engagement of at least one axial groove carried on the inner surface of the body and at least one groove formed on the periphery of the piston, the other typically including the following components, possibly in the form of a monobloc part:
a base-plate anchored to the body in terms of axial movement, but free in rotation, the anchoring to the body being achieved typically by clipping or snapping-on,
a threaded screw, integral with the base-plate, carrying and engaging with the piston forming a nut,
a toothed wheel for driving the screw, which may possibly form all or part of the bottom, a toothed wheel which allows the user to move the stick shaped cosmetic product axially, and therefore to make it rise to the upper orifice of the body, as it is consumed.
In a known way, the piston and the base-plate have apertures which allow the dispenser to be filled through the bottom, the dispenser being closed by its typically leakproof cap.
In an equally well known way, the dispenser is formed by assembling, particularly by snapping on or clipping, the propellant device into the body, the other parts of the dispenser also being generally so assembled, reversibly in terms of the cap, and irreversibly in terms of the toothed wheel activating said screw.
Thus we may cite, by way of examples of patents describing dispensers, French patent application No. 00 04425, French patent No 2 573 734, of again European patent No 462 925.
Prior art sticks include a body forming a relatively thick wall, manufacturing which poses problems of production rates and dimensional stability, particularly given the changes in viscosity resulting from the different colouring materials or pigments used to customise the sticks as a function of different customer requirements.
Furthermore, industrially manufactured prior art sticks are restricted to cross-sections or shapes that have relatively high radii of curvature, typically above 20 mm, which is to ensure they are leakproof: indeed, it is not possible to ensure the industrial production of parts moulded in plastic material intended to engage in a leakproof way when these parts have plane surfaces connecting with angles with a low radius of curvature, since leaks are still able to occur as a result of hollowing out or setting back in moulding. In fact, since said stick-form cosmetic product is typically soft and most often includes a volatile constituent, it is important for the dispenser to be leakproof, whether at the upper part of the dispenser between said cap and the body, or at the lower part of the dispenser between the body, the base-plate and the toothed wheel.
The main subject of the invention is a stick which is able to be manufactured at a high throughput while retaining the required dimensional stability. Another subject of the invention is constituted by sticks whose external cross-section or shape includes areas with a low radius of curvature, i.e. a radius of curvature typically below 30 mm, most often below 10 mm, or even lower than 1 mm.
According to the invention, the dispenser of a product, typically of a stick-form cosmetic product, includes a body forming a lateral wall of a moulded plastic material, delimiting a central cavity intended to contain said product, with, at its upper end, an upper orifice, and, at its lower end, typically a bottom including a circular lower orifice, a cap intended to seal said upper orifice, a propellant device including a base-plate and a piston, said base-plate, typically fitted with a channel or hollowed-out part, engaging with said lower orifice typically by a means of assembly that provides a rotation of said base-plate relative to said lateral wall or said bottom, said base-plate including a so-called xe2x80x9cmalexe2x80x9d helical thread axial screw, said piston including a support for said product, typically open-work with a channel, and a central part with a so-called xe2x80x9cfemalexe2x80x9d thread engaging by screwing with said axial screw, a toothed wheel of external radius R engaging in rotation with said base-plate to rotate said axial screw, and a means of sealing said lower orifice and/or said channel, and is characterised in that said lateral wall includes an assembly:
a) of an inner jacket including an inner tubular part, of area cross-section Si and thickness Ec, forming at an upper end said upper orifice and including at a lower end said lower orifice, said inner jacket typically delimiting said central cavity,
b) and an outer body including an outer tubular part of area cross-section Se greater than Si and thickness Ei, said thicknesses Ec and Ei being taken typically below 2 mm, so as to be able to manufacture said typically rigid dispenser using high throughput moulding and without dimensional distortion of said inner jacket and said outer body of plastic material, and in such a way that, since said inner tubular part is part of or is included in said outer tubular part and cannot therefore be seen from the side, said outer body is able to have a cross-section different from that of said inner jacket, with in particular different radii of curvature for said outer body and for said inner jacket.
As the applicant has pointed cut, the dispenser according to the invention resolves the essential problem which is to be able to manufacture with a high throughput dispensers that are free from manufacturing defects arising particularly from distortions, deformations or warping in the walls of dispensers made of thermoplastic materials.
The invention applies to all types of dispenser, including cylindrical dispensers.
Furthermore, by using an inner jacket and an outer body to form the lateral wall of the body of the dispenser, it is possible to obtain dispensers with shapes that have been inaccessible until now and to resolute simultaneously the problem of production rates, that of dimensional stability, as well as that of the radii of curvature, without increasing the material cost of said dispenser, and while retaining the degree of leaktightness required for said dispenser.
Thus, the invention offers an original design for dispensers wherein, in the main, an inner jacket provides the majority of the technical functions, particularly in relation to leaktightness, whereas the outer body provides the majority of the functions of decoration or external appearance while keeping said inner jacket largely out of sight.